* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* public interface NestedInteger {
* // Constructor initializes an empty nested list.
* public NestedInteger();
* // Constructor initializes a single integer.
* public NestedInteger(int value);
* // @return true if this NestedInteger holds a single integer, rather than a nested list.
* public boolean isInteger();
* // @return the single integer that this NestedInteger holds, if it holds a single integer
* // Return null if this NestedInteger holds a nested list
* public Integer getInteger();
* // Set this NestedInteger to hold a single integer.
* public void setInteger(int value);
* // Set this NestedInteger to hold a nested list and adds a nested integer to it.
* public void add(NestedInteger ni);
* // @return the nested list that this NestedInteger holds, if it holds a nested list
* // Return null if this NestedInteger holds a single integer
* public List<NestedInteger> getList();
public NestedInteger deserialize(String s) {
if (s.charAt(0) != '[') {
return new NestedInteger(Integer.parseInt(s));
Stack<NestedInteger> stack = new Stack<>();
NestedInteger res = null;
NestedInteger curNI = new NestedInteger();
curNI = new NestedInteger();
else if (c == '-' || Character.isDigit(c)) {
while (i < n && Character.isDigit(s.charAt(i))) {
val = 10 * val + s.charAt(i) - '0';
// return back last position, because we will increase i in the end
curNI = new NestedInteger(sign * val);